Inhibition of lipid droplet accumulation by Solanum nigrum by suppressing adipogenesis and inducing lipolysis, thermogenesis and autophagy in 3T3‑L1 cells

It has been reported that Solanum nigrum exhibits anti‑obesity effects in animal models induced by a high‑fat diet. However, research on how Solanum nigrum exerts its anti‑obesity effects is currently limited. Thus, the present study focused on identifying the mechanism of action associated with the anti‑obesity activity of Solanum nigrum aerial part (SNAP), which significantly inhibited the accumulation of lipid droplets in differentiating 3T3‑L1 cells. Intracellular lipid accumulation in 3T3‑L1 cells was analyzed by Oil‑Red O staining and glycerol content was analyzed using an ELISA kit. In addition, changes in protein expression within 3T3‑L1 cells were analyzed using western blot analysis. It decreased the expression level of adipogenic proteins such as CCAAT/enhancer‑binding protein α, Peroxisome proliferator‑activated receptor γ, fatty acid binding protein 4, and adiponectin. In addition, SNAP increased the expression levels of lipolytic proteins, such as adipose triglyceride lipase and hormone‑sensitive lipase, while decreasing perilipin‑1. The treatment of fully differentiated 3T3‑L1 cells increased the free glycerol levels. SNAP treatment resulted in increased AMP‑activated protein kinase phosphorylation and the expression levels of thermogenic proteins (peroxisome proliferator‑activated receptor‑γ coactivator 1‑α, PR domain containing 16 and uncoupling protein 1) and an autophagic protein (LC3‑II). Overall, these results suggested that SNAP inhibited lipid droplet accumulation by suppressing adipogenesis and promoting lipolysis, thermogenesis and autophagy.